Stewart, 63, told The Chronicle via text that he was tested Tuesday at the behest of his doctor after developing congestion and a cough this week; according to Stewart, Palomar Medical Center in Poway, near his San Diego-area home, is conducting tests night and day. Stewart, who does not have a fever, was asked to quarantine for three to five days as he awaits results. “I’m doing well,” Stewart texted. “I’m not worried, I’m being safe!”

According to the Chronicle, Stewart is an analyst on A’s pre-and post-game television broadcasts. Since retiring after the 1995 season, Stewart also has tried his hand as an agent and general manager.

In 16 MLB seasons, Stewart won three World Series titles, one with the Los Angeles Dodgers in 1981, one with A’s in 1989 and one with the Toronto Blue Jays in 1993. In fact, Stewart was the World Series MVP in 1989, going 2-0 with a 1.69 ERA against the San Francisco Giants. Stewart also was the ALCS MVP in 1990 and 1993.

Stewart won at least 20 games in four straight seasons beginning in 1987 and finished in the top four of voting for the American League Cy Young Award each season. Yet he earned just one All-Star bid during that run.